Proposals have already been made to replace the single main beam headlamp which is generally used on each side of a vehicle by a set of two identical juxtaposed headlamps, thereby providing greater illumination at long distances by increasing the amount of light flux emitted.
This also gives rise to an increase in illumination at short distances (in particular at distances of less than 30 meters), and this is undesirable for obtaining good visibility at a distance since the brightly illuminated nearby regions make it difficult to see more distant regions even if they are more brightly illuminated than usual. In other words, increasing the total emitted light flux by using a pair of identical headlamps to replace a single headlamp merely serves to accentuate the illumination gradient around the area which can be seen properly.
Preferred implementations of the present invention seek to mitigate this difficulty by means of a two-headlamp main beam unit which provides a better distribution of illumination as a function of distance, and thereby increases long distance illumination relative to conventional solutions.